/*	$OpenBSD: rf_parityscan.c,v 1.6 2000/08/08 16:07:44 peter Exp $	*/
/*	$NetBSD: rf_parityscan.c,v 1.9 2000/05/28 03:00:31 oster Exp $	*/

/*
 * Copyright (c) 1995 Carnegie-Mellon University.
 * All rights reserved.
 *
 * Author: Mark Holland
 *
 * Permission to use, copy, modify and distribute this software and
 * its documentation is hereby granted, provided that both the copyright
 * notice and this permission notice appear in all copies of the
 * software, derivative works or modified versions, and any portions
 * thereof, and that both notices appear in supporting documentation.
 *
 * CARNEGIE MELLON ALLOWS FREE USE OF THIS SOFTWARE IN ITS "AS IS"
 * CONDITION.  CARNEGIE MELLON DISCLAIMS ANY LIABILITY OF ANY KIND
 * FOR ANY DAMAGES WHATSOEVER RESULTING FROM THE USE OF THIS SOFTWARE.
 *
 * Carnegie Mellon requests users of this software to return to
 *
 *  Software Distribution Coordinator  or  Software.Distribution@CS.CMU.EDU
 *  School of Computer Science
 *  Carnegie Mellon University
 *  Pittsburgh PA 15213-3890
 *
 * any improvements or extensions that they make and grant Carnegie the
 * rights to redistribute these changes.
 */

/*****************************************************************************
 *
 * rf_parityscan.c -- Misc utilities related to parity verification.
 *
 *****************************************************************************/

#include "rf_types.h"
#include "rf_raid.h"
#include "rf_dag.h"
#include "rf_dagfuncs.h"
#include "rf_dagutils.h"
#include "rf_mcpair.h"
#include "rf_general.h"
#include "rf_engine.h"
#include "rf_parityscan.h"
#include "rf_map.h"


/*****************************************************************************
 *
 * Walk through the entire arry and write new parity.
 * This works by creating two DAGs, one to read a stripe of data and one to
 * write new parity. The first is executed, the data is xored together, and
 * then the second is executed. To avoid constantly building and tearing down
 * the DAGs, we create them a priori and fill them in with the mapping
 * information as we go along.
 *
 * There should never be more than one thread running this.
 *
 *****************************************************************************/
int
rf_RewriteParity(RF_Raid_t *raidPtr)
{
	RF_RaidLayout_t *layoutPtr = &raidPtr->Layout;
	RF_AccessStripeMapHeader_t *asm_h;
	int ret_val;
	int rc;
	RF_PhysDiskAddr_t pda;
	RF_SectorNum_t i;

	if (raidPtr->Layout.map->faultsTolerated == 0) {
		/* There isn't any parity. Call it "okay." */
		return (RF_PARITY_OKAY);
	}
	if (raidPtr->status[0] != rf_rs_optimal) {
		/*
		 * We're in degraded mode. Don't try to verify parity now !
		 * XXX: This should be a "we don't want to", not a
		 * "we can't" error.
		 */
		return (RF_PARITY_COULD_NOT_VERIFY);
	}

	ret_val = 0;

	pda.startSector = 0;
	pda.numSector = raidPtr->Layout.sectorsPerStripeUnit;
	rc = RF_PARITY_OKAY;

	for (i = 0; i < raidPtr->totalSectors && rc <= RF_PARITY_CORRECTED;
	     i += layoutPtr->dataSectorsPerStripe) {
		if (raidPtr->waitShutdown) {
			/*
			 * Someone is pulling the plug on this set...
			 * Abort the re-write.
			 */
			return (1);
		}
		asm_h = rf_MapAccess(raidPtr, i,
		    layoutPtr->dataSectorsPerStripe, NULL, RF_DONT_REMAP);
		raidPtr->parity_rewrite_stripes_done =
			i / layoutPtr->dataSectorsPerStripe ;
		rc = rf_VerifyParity(raidPtr, asm_h->stripeMap, 1, 0);
		switch (rc) {
		case RF_PARITY_OKAY:
		case RF_PARITY_CORRECTED:
			break;
		case RF_PARITY_BAD:
			printf("Parity bad during correction.\n");
			ret_val = 1;
			break;
		case RF_PARITY_COULD_NOT_CORRECT:
			printf("Could not correct bad parity.\n");
			ret_val = 1;
			break;
		case RF_PARITY_COULD_NOT_VERIFY:
			printf("Could not verify parity.\n");
			ret_val = 1;
			break;
		default:
			printf("Bad rc=%d from VerifyParity in"
			    " RewriteParity.\n", rc);
			ret_val = 1;
		}
		rf_FreeAccessStripeMap(asm_h);
	}
	return (ret_val);
}


/*****************************************************************************
 *
 * Verify that the parity in a particular stripe is correct.
 * We validate only the range of parity defined by parityPDA, since
 * this is all we have locked. The way we do this is to create an asm
 * that maps the whole stripe and then range-restrict it to the parity
 * region defined by the parityPDA.
 *
 *****************************************************************************/
int
rf_VerifyParity(RF_Raid_t *raidPtr, RF_AccessStripeMap_t *aasm, int correct_it,
    RF_RaidAccessFlags_t flags)
{
	RF_PhysDiskAddr_t *parityPDA;
	RF_AccessStripeMap_t *doasm;
	RF_LayoutSW_t *lp;
	int lrc, rc;

	lp = raidPtr->Layout.map;
	if (lp->faultsTolerated == 0) {
		/*
		 * There isn't any parity. Call it "okay."
		 */
		return (RF_PARITY_OKAY);
	}
	rc = RF_PARITY_OKAY;
	if (lp->VerifyParity) {
		for (doasm = aasm; doasm; doasm = doasm->next) {
			for (parityPDA = doasm->parityInfo; parityPDA;
			     parityPDA = parityPDA->next) {
				lrc = lp->VerifyParity(raidPtr,
				    doasm->raidAddress, parityPDA, correct_it,
				    flags);
				if (lrc > rc) {
					/*
					 * see rf_parityscan.h for why this
					 * works.
					 */
					rc = lrc;
				}
			}
		}
	} else {
		rc = RF_PARITY_COULD_NOT_VERIFY;
	}
	return (rc);
}

int
rf_VerifyParityBasic(RF_Raid_t *raidPtr, RF_RaidAddr_t raidAddr,
    RF_PhysDiskAddr_t *parityPDA, int correct_it, RF_RaidAccessFlags_t flags)
{
	RF_RaidLayout_t *layoutPtr = &(raidPtr->Layout);
	RF_RaidAddr_t startAddr = rf_RaidAddressOfPrevStripeBoundary(layoutPtr,
	    raidAddr);
	RF_SectorCount_t numsector = parityPDA->numSector;
	int numbytes = rf_RaidAddressToByte(raidPtr, numsector);
	int bytesPerStripe = numbytes * layoutPtr->numDataCol;
	RF_DagHeader_t *rd_dag_h, *wr_dag_h;	/* Read, write dag. */
	RF_DagNode_t *blockNode, *unblockNode, *wrBlock, *wrUnblock;
	RF_AccessStripeMapHeader_t *asm_h;
	RF_AccessStripeMap_t *asmap;
	RF_AllocListElem_t *alloclist;
	RF_PhysDiskAddr_t *pda;
	char *pbuf, *buf, *end_p, *p;
	int i, retcode;
	RF_ReconUnitNum_t which_ru;
	RF_StripeNum_t psID = rf_RaidAddressToParityStripeID(layoutPtr,
	    raidAddr, &which_ru);
	int stripeWidth = layoutPtr->numDataCol + layoutPtr->numParityCol;
	RF_AccTraceEntry_t tracerec;
	RF_MCPair_t *mcpair;

	retcode = RF_PARITY_OKAY;

	mcpair = rf_AllocMCPair();
	rf_MakeAllocList(alloclist);
	RF_MallocAndAdd(buf, numbytes * (layoutPtr->numDataCol +
	    layoutPtr->numParityCol), (char *), alloclist);
	/* Use calloc to make sure buffer is zeroed. */
	RF_CallocAndAdd(pbuf, 1, numbytes, (char *), alloclist);
	end_p = buf + bytesPerStripe;

	rd_dag_h = rf_MakeSimpleDAG(raidPtr, stripeWidth, numbytes, buf,
	    rf_DiskReadFunc, rf_DiskReadUndoFunc,
	    "Rod", alloclist, flags, RF_IO_NORMAL_PRIORITY);
	blockNode = rd_dag_h->succedents[0];
	unblockNode = blockNode->succedents[0]->succedents[0];

	/* Map the stripe and fill in the PDAs in the dag. */
	asm_h = rf_MapAccess(raidPtr, startAddr,
	    layoutPtr->dataSectorsPerStripe, buf, RF_DONT_REMAP);
	asmap = asm_h->stripeMap;

	for (pda = asmap->physInfo, i = 0; i < layoutPtr->numDataCol;
	     i++, pda = pda->next) {
		RF_ASSERT(pda);
		rf_RangeRestrictPDA(raidPtr, parityPDA, pda, 0, 1);
		RF_ASSERT(pda->numSector != 0);
		if (rf_TryToRedirectPDA(raidPtr, pda, 0))
			goto out;	/*
					 * No way to verify parity if disk is
					 * dead. Return w/ good status.
					 */
		blockNode->succedents[i]->params[0].p = pda;
		blockNode->succedents[i]->params[2].v = psID;
		blockNode->succedents[i]->params[3].v =
		    RF_CREATE_PARAM3(RF_IO_NORMAL_PRIORITY, 0, 0, which_ru);
	}

	RF_ASSERT(!asmap->parityInfo->next);
	rf_RangeRestrictPDA(raidPtr, parityPDA, asmap->parityInfo, 0, 1);
	RF_ASSERT(asmap->parityInfo->numSector != 0);
	if (rf_TryToRedirectPDA(raidPtr, asmap->parityInfo, 1))
		goto out;
	blockNode->succedents[layoutPtr->numDataCol]->params[0].p =
	    asmap->parityInfo;

	/* Fire off the DAG. */
	bzero((char *) &tracerec, sizeof(tracerec));
	rd_dag_h->tracerec = &tracerec;

	if (rf_verifyParityDebug) {
		printf("Parity verify read dag:\n");
		rf_PrintDAGList(rd_dag_h);
	}
	RF_LOCK_MUTEX(mcpair->mutex);
	mcpair->flag = 0;
	rf_DispatchDAG(rd_dag_h, (void (*) (void *)) rf_MCPairWakeupFunc,
	    (void *) mcpair);
	while (!mcpair->flag)
		RF_WAIT_COND(mcpair->cond, mcpair->mutex);
	RF_UNLOCK_MUTEX(mcpair->mutex);
	if (rd_dag_h->status != rf_enable) {
		RF_ERRORMSG("Unable to verify parity:  can't read the"
		            " stripe.\n");
		retcode = RF_PARITY_COULD_NOT_VERIFY;
		goto out;
	}
	for (p = buf; p < end_p; p += numbytes) {
		rf_bxor(p, pbuf, numbytes, NULL);
	}
	for (i = 0; i < numbytes; i++) {
#if 0
		if (pbuf[i] != 0 || buf[bytesPerStripe + i] != 0) {
			printf("Bytes: %d %d %d\n", i, pbuf[i],
			    buf[bytesPerStripe + i]);
		}
#endif
		if (pbuf[i] != buf[bytesPerStripe + i]) {
			if (!correct_it)
				RF_ERRORMSG3("Parity verify error: byte %d of"
				    " parity is 0x%x should be 0x%x.\n", i,
				    (u_char) buf[bytesPerStripe + i],
				    (u_char) pbuf[i]);
			retcode = RF_PARITY_BAD;
			break;
		}
	}

	if (retcode && correct_it) {
		wr_dag_h = rf_MakeSimpleDAG(raidPtr, 1, numbytes, pbuf,
		    rf_DiskWriteFunc, rf_DiskWriteUndoFunc,
		    "Wnp", alloclist, flags, RF_IO_NORMAL_PRIORITY);
		wrBlock = wr_dag_h->succedents[0];
		wrUnblock = wrBlock->succedents[0]->succedents[0];
		wrBlock->succedents[0]->params[0].p = asmap->parityInfo;
		wrBlock->succedents[0]->params[2].v = psID;
		wrBlock->succedents[0]->params[3].v =
		    RF_CREATE_PARAM3(RF_IO_NORMAL_PRIORITY, 0, 0, which_ru);
		bzero((char *) &tracerec, sizeof(tracerec));
		wr_dag_h->tracerec = &tracerec;
		if (rf_verifyParityDebug) {
			printf("Parity verify write dag:\n");
			rf_PrintDAGList(wr_dag_h);
		}
		RF_LOCK_MUTEX(mcpair->mutex);
		mcpair->flag = 0;
		rf_DispatchDAG(wr_dag_h, (void (*) (void *))
		    rf_MCPairWakeupFunc, (void *) mcpair);
		while (!mcpair->flag)
			RF_WAIT_COND(mcpair->cond, mcpair->mutex);
		RF_UNLOCK_MUTEX(mcpair->mutex);
		if (wr_dag_h->status != rf_enable) {
			RF_ERRORMSG("Unable to correct parity in VerifyParity:"
			    "  can't write the stripe.\n");
			retcode = RF_PARITY_COULD_NOT_CORRECT;
		}
		rf_FreeDAG(wr_dag_h);
		if (retcode == RF_PARITY_BAD)
			retcode = RF_PARITY_CORRECTED;
	}
out:
	rf_FreeAccessStripeMap(asm_h);
	rf_FreeAllocList(alloclist);
	rf_FreeDAG(rd_dag_h);
	rf_FreeMCPair(mcpair);
	return (retcode);
}

int
rf_TryToRedirectPDA(RF_Raid_t *raidPtr, RF_PhysDiskAddr_t *pda, int parity)
{
	if (raidPtr->Disks[pda->row][pda->col].status == rf_ds_reconstructing) {
		if (rf_CheckRUReconstructed(raidPtr->reconControl[pda->row]
		     ->reconMap, pda->startSector)) {
			if (raidPtr->Layout.map->flags & RF_DISTRIBUTE_SPARE) {
				RF_RowCol_t or = pda->row, oc = pda->col;
				RF_SectorNum_t os = pda->startSector;
				if (parity) {
					(raidPtr->Layout.map->MapParity)
					    (raidPtr, pda->raidAddress,
					     &pda->row, &pda->col,
					     &pda->startSector, RF_REMAP);
					if (rf_verifyParityDebug)
						printf("VerifyParity: Redir P"
						    " r %d c %d sect %ld ->"
						    " r %d c %d sect %ld.\n",
						    or, oc, (long) os,
						    pda->row, pda->col,
						    (long) pda->startSector);
				} else {
					(raidPtr->Layout.map->MapSector)
					    (raidPtr, pda->raidAddress,
					     &pda->row, &pda->col,
					     &pda->startSector, RF_REMAP);
					if (rf_verifyParityDebug)
						printf("VerifyParity: Redir D"
						    " r %d c %d sect %ld ->"
						    " r %d c %d sect %ld.\n",
						    or, oc, (long) os,
						    pda->row, pda->col,
						    (long) pda->startSector);
				}
			} else {
				RF_RowCol_t spRow =
				    raidPtr->Disks[pda->row][pda->col].spareRow;
				RF_RowCol_t spCol =
				    raidPtr->Disks[pda->row][pda->col].spareCol;
				pda->row = spRow;
				pda->col = spCol;
			}
		}
	}
	if (RF_DEAD_DISK(raidPtr->Disks[pda->row][pda->col].status))
		return (1);
	return (0);
}


/*****************************************************************************
 *
 * Currently a stub.
 *
 * Takes as input an ASM describing a write operation and containing one
 * failure, and verifies that the parity was correctly updated to reflect the
 * write.
 *
 * If it's a data unit that has failed, we read the other data units in the
 * stripe and the parity unit, XOR them together, and verify that we get the
 * data intended for the failed disk. Since it's easy, we also validate that
 * the right data got written to the surviving data disks.
 *
 * If it's the parity that failed, there's really no validation we can do
 * except the above verification that the right data got written to all disks.
 * This is because the new data intended for the failed disk is supplied in
 * the ASM, but this is of course not the case for the new parity.
 *
 *****************************************************************************/
int
rf_VerifyDegrModeWrite(RF_Raid_t *raidPtr, RF_AccessStripeMapHeader_t *asmh)
{
	return (0);
}


/*
 * Creates a simple DAG with a header, a block-recon node at level 1,
 * nNodes nodes at level 2, an unblock-recon node at level 3, and
 * a terminator node at level 4. The stripe address field in
 * the block and unblock nodes are not touched, nor are the pda
 * fields in the second-level nodes, so they must be filled in later.
 *
 * Commit point is established at unblock node - this means that any
 * failure during dag execution causes the dag to fail.
 */
RF_DagHeader_t *
rf_MakeSimpleDAG(RF_Raid_t *raidPtr, int nNodes, int bytesPerSU, char *databuf,
    int (*doFunc) (RF_DagNode_t * node), int (*undoFunc) (RF_DagNode_t * node),
    char *name	/* Node names at the second level. */,
    RF_AllocListElem_t *alloclist, RF_RaidAccessFlags_t flags, int priority)
{
	RF_DagHeader_t *dag_h;
	RF_DagNode_t *nodes, *termNode, *blockNode, *unblockNode;
	int i;

	/*
	 * Create the nodes, the block & unblock nodes, and the terminator
	 * node.
	 */
	RF_CallocAndAdd(nodes, nNodes + 3, sizeof(RF_DagNode_t),
	    (RF_DagNode_t *), alloclist);
	blockNode = &nodes[nNodes];
	unblockNode = blockNode + 1;
	termNode = unblockNode + 1;

	dag_h = rf_AllocDAGHeader();
	dag_h->raidPtr = (void *) raidPtr;
	dag_h->allocList = NULL;	/* We won't use this alloc list. */
	dag_h->status = rf_enable;
	dag_h->numSuccedents = 1;
	dag_h->creator = "SimpleDAG";

	/*
	 * This dag can not commit until the unblock node is reached.
	 * Errors prior to the commit point imply the dag has failed.
	 */
	dag_h->numCommitNodes = 1;
	dag_h->numCommits = 0;

	dag_h->succedents[0] = blockNode;
	rf_InitNode(blockNode, rf_wait, RF_FALSE, rf_NullNodeFunc,
	    rf_NullNodeUndoFunc, NULL, nNodes, 0, 0, 0, dag_h,
	    "Nil", alloclist);
	rf_InitNode(unblockNode, rf_wait, RF_TRUE, rf_NullNodeFunc,
	    rf_NullNodeUndoFunc, NULL, 1, nNodes, 0, 0, dag_h,
	    "Nil", alloclist);
	unblockNode->succedents[0] = termNode;
	for (i = 0; i < nNodes; i++) {
		blockNode->succedents[i] = unblockNode->antecedents[i]
					 = &nodes[i];
		unblockNode->antType[i] = rf_control;
		rf_InitNode(&nodes[i], rf_wait, RF_FALSE, doFunc, undoFunc,
		    rf_GenericWakeupFunc, 1, 1, 4, 0, dag_h, name, alloclist);
		nodes[i].succedents[0] = unblockNode;
		nodes[i].antecedents[0] = blockNode;
		nodes[i].antType[0] = rf_control;
		nodes[i].params[1].p = (databuf + (i * bytesPerSU));
	}
	rf_InitNode(termNode, rf_wait, RF_FALSE, rf_TerminateFunc,
	    rf_TerminateUndoFunc, NULL, 0, 1, 0, 0, dag_h, "Trm", alloclist);
	termNode->antecedents[0] = unblockNode;
	termNode->antType[0] = rf_control;
	return (dag_h);
}
